In using RTSS to limit frames to 30 however when I do this the 'main thread', be it in P3D or MSFS always sits close to maxed out, whereas w/ vsync to 30Hz screen I don't see this at all, except when there is extreme demand on the main thread, so as it should be.  Any way to setup RTSS so this does not happen, so that the main thread is only tasked w/ what is need to maintain the 30fps, as it appears to be when we vsync to a 30Hz screen?

I just looked and it does indeed max out thread 0, however the overall CPU load is between 30 and 40%, this with Prepar3D and Hyperthreading off. 

Do you think the maxed out main thread is detrimental to overall performance? I would not know any alternative setting in RTSS.

22 minutes ago, hjsmuc said:

I just looked and it does indeed max out thread 0, however the overall CPU load is between 30 and 40%, this with Prepar3D and Hyperthreading off. 

Do you think the maxed out main thread is detrimental to overall performance? I would not know any alternative setting in RTSS.

My guess Hans is that when you see the main thread maxed out this means the main thread is being asked to pre-render (may be the wrong term for this not sure) as many as it possibly can, versus when I vsync to my 30Hz capable screen this does not happen.  To me, this implies the CPU not only is creating more frames than needed to hit the 30fps limit, but is also perhaps not going to be as responsive to new demands given to it, for example leave some headroom for a PMDG plane for example.   This may be pure fantasy, but I can tell you w/ vsync to 30hz screen even hyperthreaded w/ all cores at 49Ghz, my CPU temp is only 45-50C.  I think the composite CPU utilization of 30 to 40% just reflects the other cores not being used much at that moment in time relative to the main thread core or LP.  As long as the application can use those other cores for various tasks that helps for sure but unless designed to do so will not give the main thread extra room, presumably, and the main thread constrains the rest of the sim.  My composite CPU utilization is in the same range in P3D, lower in MSFS.

So to try to answer your question which is the right one, is it detrimental to have the main thread be maxed out?  I think hte only way you can answer that is looking at smoothness/stutter-free wheirin the sim runs steadily at 30fps as intended, unless the main thread is maxed and there is more demand coming into it.  It could be that the vsync to 30Hz approach DOES in fact leave headroom for this sort of condition.  Are there less areas in a given flight where the CPU is asked to produce more than it can (thereby lowering frame rate to <30 and with it onset of stuttering) compared to using RTSS to limit frames where the main thread always appears maxed?  I'm not really sure as I haven't used the RTSS method other than to note the main thread becomes maxed and that didn't sound good.  Though as I say I'm not really sure.  I don't suffer from having difficulties w/ a 30Hz LCD monitor so this option is my preferred one it just has no downside in both P3D and MSFS.

Edited November 6, 20205 yr by Noel

I will try to do some comparison flights with frame rate limiting with RTSS and Nvidia to see if I can spot differences. However, as all systems are different we all use different set-ups it will be difficult to come to meaningful conclusions, I am afraid. Thanks for bringing this up, though. 

I read somewhere that it is a "false reading" by Task Manager.

Check the CPU Core Temps to see if Core0 is indeed running flat out..

I am using RTSS scanline x/2 for MSFS, but using NCP fps lock = 30 for P3DV5.

Both offer smooth flight.

The reason I switched P3D off RTSS, is that I was getting flickering popup windows.

Edited November 6, 20205 yr by Bert Pieke

20 hours ago, Bert Pieke said:

I read somewhere that it is a "false reading" by Task Manager.

Check the CPU Core Temps to see if Core0 is indeed running flat out..

I am using RTSS scanline x/2 for MSFS, but using NCP fps lock = 30 for P3DV5.

Both offer smooth flight.

The reason I switched P3D off RTSS, is that I was getting flickering popup windows.

I just checked this out and while the main thread is fluctuating around 90-98% in a low demand setting core temp for that core is only 39-41C so that looks good.  Having the main thread reporting as high is the same whether you look at TM or other apps that report CPU use per core, for some reason.

Now we are flying in a very busy area.  With the RTSS method I'm seeing frame rate run at 30 as it's supposed to if able, and yet every few seconds or so it will go to 29, then back to 30, and with this considerable stuttering.  So I go back to vsync to 30Hz and almost no stutters, main thread at around 62%, and locked at 30.  Whatever the approach used in RTSS it does not compare as favorably to what vsync to 30Hz offers.   The true holy grail be being able to maintain 60fps so you can then vsync to 60.  I understand a true GSYNC monitor offers intermediate levels of this approach to limiting frames.

Edited November 7, 20205 yr by Noel